Hematopoietic stem cell transplantation (SCT) is an intensive, costly and effective treatment for many malignant and non-malignant diseases. Long-term survivors are at risk for diverse late effects. Complications occurring beyond the first year post-SCT include relapsed disease, toxic effects of myeloablative preparative regimens, compromised immunity with consequent infections, graft-versus-host disease and new cancers. These and other problems contribute to excess mortality compared to the normal population, impaired functional status and inability to work. As increasing numbers of patients receive SCT and survive, understanding the frequency and severity of late effects takes on greater importance. New SCT technologies, designed primarily to reduce early transplant-related complications, may have little effect on or even worsen late problems. Using the resources of the International Bone Marrow Transplant Registry and the Autologous Blood and Marrow Transplant Registry, the candidate's research program will include a multi-faceted evaluation of SCT, including consideration of SCT costs, with on emphasis on late consequences. The specific research aims of this proposal are to: 1) to determine the incidence of and risk factors for late adverse events among persons surviving two or more years after allogeneic or autologous hematopoietic stem cell transplantation; and, 2) to compare HLA-identical sibling bone marrow versus peripheral blood stem cell transplants for leukemia for incidence and severity of chronic graft-versus-host disease, risk of relapse, direct medical costs and functional status. Completion of these projects will contribute in a meaningful way to our understanding of the long term consequences of stem cell transplantation. They also, in concert with formal course work, close mentoring, and collaboration with experts in SCT, statistics, epidemiology, and economics will develop the candidate's competence in many aspects of outcomes research, including study design, management and analysis of large databases, statistical methods for survival and cost analyses, and multi-center collaboration.